There are multiple bugs demonstrated by the interrupts test.
The first failing test is measuring the number of cycles that elapse between scanlines in fast mode. Should be either 25 or 26, but MESS returns 36.
After forcing that one to pass, the second failing test waits for a single interrupt to occur, but occasionally two are issued in succession, and so the interrupt count is wrong.
After forcing that one to pass, the third failing test wants to enable an interrupt for each scanline in SHGR mode, but only the first line issues any interrupt.

If mount the disk on S6D1 but start from basic prompt with "pr#6", instead clicking on menu Reboot 6 icon, it will report Apple2gs 2.25meg!
Now Super-high resolution works and it look same / similar to MESS! (but the question is does it looks the same on a real GS too?)

(Note: press RMB on ActiveGS window to get into disk mount menu)
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